Silicon template preparation for the fabrication of thin patterned gold films via template stripping

Abstract

Metallic nanostructures play an important role in the vast field of modern nanophotonics, which ranges from the life sciences to biomedicine and beyond. Gold is a commonly-used and attractive material for plasmonics in the visible wavelength range, most importantly due to its chemical stability. In the present work, we focused on the different methods of plasmonic nanostructure fabrication that possess the greatest potential for cost-efficient fabrication. Initially, reusable (1 0 0) silicon templates were prepared. For this purpose, three different lithography methods (i.e. e-beam, optical, and nanoparticle lithography) were used that correspond to the desired structural scales. The application of a subsequent anisotropic crystal orientation-dependent wet etching process produced well-defined pyramidal structures in a wide variety of sizes, ranging from several microns to less than 100 nm. Finally, a 200 nm-thick gold layer was deposited by means of confocal sputtering on the silicon templates and stripped in order to obtain gold films that feature a surface replica of the initial template structure. The surface roughness that was achieved on the stripped films corresponds well with the roughness of the template used. This makes it possible to prepare cost-efficient high-quality structured films in large quantities with little effort. The gold films produced were thoroughly characterized, particularly with respect to their plasmonic response.